[√(2x+1)]+3=0 for x=4 [√(2*4+1)]+3=0 [√(9)]+3=0 3+3=0----------6 is not zero therefore the solution is not correct for x=4
[√(2x+1)]+3=0--------> [√(2x+1)]=-3---------> <span>There is no real solution for that equation </span>Because (2x+1) >= 0 the solution is with complex numbers
